View Full Version : learning experience: first salt print

05-20-2009, 08:26 PM
Well, finally got around to printing an image after running some Stouffer step wedges and ChartThrob tests to determine Dmax and generate a PS curve for salt printing. Boy does salt print have a LONG tone scale: a full 9 stops and maybe more (my scanner can see tones into step 21, so it's possible there is more yet out there). The digital negative has to be very, very dense to block enough UV light to print this, but the result is pretty good for now. Still have to do some tweaking of the PS curve to linearize the tones in the print. And next steps are to try gold toning and then sizing the paper with gelatin to reduce paper grain and make it more brilliant.

Oh, and I forgot to flip the file in PS before printing the negative, hence the backwards "21"! OOOPS! ;)

Printed on Fabriano Aristico (a wonderful paper but quite grainy) from a digital negative via a very convoluted workflow!

Attached files http://f295.f295.org/uploads/f295b_4661.jpg (http://f295.f295.org/uploads/f295b_4661.jpg)

05-21-2009, 01:45 AM
A great first salt print. Please report more of your experiences and the "very convoluted workflow".

The "21" in the picture must be the reason that you can see tones into step 21. ;)

05-21-2009, 02:44 AM
well I'm still a novice at this ... but hopefully as I keep plugging away at this I'll get some of the kinks worked out. Right now, the mid and high tones are quite mushy in here, which tells me I need more density in the negative. My curve needs tweaking to pull up those tones so that they match what I see on my monitor.

As for my workflow. I take a digital file, add a PS curve (more on this below), flatten, flip (horizontal), invert and then print it on Pictorico OHP (overhead transparency film). Since metal particles can interact with some alt processes, I hand tear (using a bone paper folder and a wooden straight edge) each sheet. I'm using Fabriano Aristico Hot Press (310 gsm iirc). For convenience, I am using Bostick and Sullivan's salt chemical kit, so I salt the paper with their solution: 12 drops for a 4x5 image area like this. Wait an hour (or a day, the paper keeps fine salted), then sensitize with 12% solution of silver nitrate (again 12 drops). Dry for another hour or so in the dark. Then expose for 7 minutes at noon-4pm sun. Wash in warm water till the milky lift off stops, then fix for 7-10 minutes in hypo, then wash for 30 minutes with water changes every 3-5 minutes.

Most of that is straightforward, but building the PS curves is proving to entail lots of testing. I'm using an Epson R2400 and having a bit of a time getting enough density in the mids and highs on the negative simply because salt has such an amazingly long contrast/tonal range. If I expose the print to get Dmax, the mids/highs tend to be muddy, like here. I'm just using the Epson printer drivers, specifically the ABW (advanced black and white) settings, and using Kevin Bjorke's ChartThrob PS script to help me get curves. Thing is the ABW lets me print the negatives in "Lighter", "Light", "Normal", "Dark", "Darker" and "Darkest" tones. So far, I haven't yet tested the Darker and Darkest charts to see if I can get more density on the negative. That's on the agenda for next time (perhaps Sunday). If the extra ink on the Darker/Darkest setting helps get more density in the negative's dark areas (highlights on the print), then I may be able to build a very nice curve. But today I got tired of printing step wedges and exposure charts, so I finally printed an image with what I had just to see some tangible "results" :)

I really like the deep brown leather tones of the untoned salt, and will be a bit sad to lose that by toning. I've heard that gold toning (which is what I'll start with) usually gives a cool tone to the image, and improves it's archival qualities too.

Tom Persinger
05-21-2009, 09:31 AM
looks good Kevin! thanks for sharing!

05-21-2009, 07:14 PM
Impressive! A good salt print is a beautiful thing. Looks like you're getting close, if not already there!
Thanks for the notes about your process, too!

05-22-2009, 09:48 AM
Salt print. Mmmmm - yummy.

That's a lot of work. Is it necessary to create a digital negative? Or will this process work with a "normal" negative?

05-22-2009, 03:59 PM
Stormy - it works with a normal negative. However, it works best with a negative that has considerable extra development to add density to the highlights. I am finding that I am not good enough to consistently match in-camera negatives to alt printing processes, but I keep trying. The carbon process is print almost as long a scale as salt - I have yet to make a negative in-camera that does full justice to either process. However, that does not mean that I can't make some wonderful prints!

Man, 21 steps! That's l - o - n - g!

05-22-2009, 08:32 PM
basically, what earl said! you -can- make an in-camera neg to print these, but if you do so, you really need to know ahead of time (i.e., before exposure and development) what process you are going to print for, as well as what tonal range that process will give using your own materials. The negative for a salt print will be quite different from a palladium, from a gum, from a bromoil, from a cyanotype.

I choose to go a hybrid path precisely because I want to be able to make digital (inkjet) prints as well as do various alt processes at will, all from the same negative. The hybrid approach is quite convoluted and involves a lot of tests (I have several stacks of step tablet and step wedges prints for both salt and cyanotype now), but its strength is flexibility: once I map the tone curve for any given process I can apply a PS curve to -any- of my files and print the image confident that it will be close to what my monitor shows (which already includes lots of PS tweaking: spotting, retouching, contrast adjustments, burning/dodging, etc.). Steep (and to be honest, sometimes very frustrating) learning curve but very powerful / flexible in the end.

05-26-2009, 10:16 AM

Liked your Salt print.

Did you expose long enough for steps 1 and 2 of step wedge to merge - thus D Max? Could not tell on my monitor when I looked at your printed step wedge result. If steps 1 and 2 have not merged that might reduce your 21 steps tonal range.

I've tried some Salt prints but getting contamination from somewhere that is causing frecking on my prints.

Gold toning will definetely change the apperance of final print.


05-27-2009, 01:20 AM
Thanks for the compliment -- I'm a complete novice and quite aware that I have a long way to go (and that this is no masterpiece print). But I am grateful for encouragement all the same.

As for your question, they aren't quite merged. It's subtle, but there is a slight difference in hand (very hard to see on the monitor though). The difference between the OHP base and the bare emulsion is even less though (the OHP base is in between the first two steps on the wedge), so the print (as opposed to the step wedge) is very, very close to Dmax. My understanding, though, is that merging them would actually lengthen the tonal scale, as every step up the line would be getting more exposure until the whitest possible (paper+emulsion) ... but, then again, I sometimes get all the positives and negatives tangled up and confused :)

I haven't retried anything since posting this (was out of town), but I'm still unsure whether my printer can actually lay down enough ink (using ABW printing methods anyway) to actually get the whole tonal range that the process has in it. Going to try re-printing the test chart using some different settings to see if I can get enough density to actually get to "white" -- if not, then I'll either have to try using QTR profiles or put salt aside in favor of processes that I can generate a digital negative that will print the full tonal scale. I am anxious to try the gold toning and gelatin sizing, but am making sure to take this all one step at a time. There's just too many variables to even attempt it haphazardly. "Baby steps! Baby steps!" ;)

Really sorry to hear about the contamination issue for you... I can imagine that tracking it down could be very troublesome and time consuming. :(